Reaction turbines are ideal for applications where there is a steady, consistent flow. They are highly efficient and work well when there is a need for positive outlet pressure (such as force mains). In some cases where variable pressure is a concern they can be used with a flywheel or quick opening bypass valve in case of grid loss. Reaction turbines are low-cost compared to Pelton turbines.
Pelton turbines are excellent for variable flows and require no flywheel or quick-opening bypass valve in the event of grid loss. They must be exhausted to the atmosphere and are more expensive than a reaction turbine.
